// 用于将页面指定内容导出成pdf

// 一. 使用之前需要先按照2个npm包
// npm install html2canvas -S --registry=https://registry.npmmirror.com/
// npm install jspdf -S --registry=https://registry.npmmirror.com/

// 二. 使用：1. 引用 2. 调用方法 3. 记得给指定容器加id
// import htmlToPdf from "@/utils/htmlToPDF";
// const printReport = () => {
//     htmlToPdf.getPdf('测试pdf',"#db-test-report");
// }

// 页面导出为pdf格式
import html2Canvas from "html2canvas";
import jsPDF from "jspdf";
import { uploadImg } from '@/api/public';

const htmlToPdf = {
    getPdf(title, id) {
        html2Canvas(document.querySelector(id), {
            allowTaint: false,
            taintTest: false,
            logging: false,
            useCORS: true,
            dpi: window.devicePixelRatio * 4, //将分辨率提高到特定的DPI 提高四倍
            scale: 4, //按比例增加分辨率
        }).then((canvas) => {
            var pdf = new jsPDF("p", "mm", "a4"); //A4纸，纵向
            var ctx = canvas.getContext("2d"),
                a4w = 190,
                a4h = 272, //A4大小，210mm x 297mm，四边各保留10mm的边距，显示区域190x277
                imgHeight = Math.floor((a4h * canvas.width) / a4w), //按A4显示比例换算一页图像的像素高度
                renderedHeight = 0;

            while (renderedHeight < canvas.height) {
                var page = document.createElement("canvas");
                page.width = canvas.width;
                page.height = Math.min(imgHeight, canvas.height - renderedHeight); //可能内容不足一页

                //用getImageData剪裁指定区域，并画到前面创建的canvas对象中
                page
                    .getContext("2d")
                    .putImageData(
                        ctx.getImageData(
                            0,
                            renderedHeight,
                            canvas.width,
                            Math.min(imgHeight, canvas.height - renderedHeight)
                        ),
                        0,
                        0
                    );
                pdf.addImage(
                    page.toDataURL("image/jpeg", 1.0),
                    "JPEG",
                    10,
                    10,
                    a4w,
                    Math.min(a4h, (a4w * page.height) / page.width)
                ); //添加图像到页面，保留10mm边距

                renderedHeight += imgHeight;
                if (renderedHeight < canvas.height) {
                    pdf.addPage(); //如果后面还有内容，添加一个空页
                }
                // delete page;
            }

            console.log(pdf)
            // pdf.save(title + ".pdf"); // PDF.save() 此方法可以将pdf直接保存本地
            let pdfData = pdf.output('datauristring') // 获取base64Pdf
            let files = dataURLtoFile(pdfData, '封面.pdf') // 将base64文件转化为流，上传oss
            uploadFiles(files)
        });
    },
};

function dataURLtoFile(dataurl, filename) {
    let arr = dataurl.split(',')
    let mime = arr[0].match(/:(.*?);/)[1]
    let bstr = atob(arr[1])
    let n = bstr.length
    let u8arr = new Uint8Array(n)
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n)
    }
    return new File([u8arr], filename, { type: mime })
}

function uploadFiles(files) {
    let data = new FormData()
    data.append('file', files)
    uploadImg(data).then(res => {
        console.log(res)
        if (res.data.code == 0) {
            // formData.value.qrcode = res.data.data.res.url
        }
    })
}

export default htmlToPdf;

